BRAF gene mutations in Castleman disease

Introduction and Objective: Castleman's Disease is a rare lymphoproliferative disorder. The association with IL-6 secretion, HIV / HHV-8 is well described, but the pathogenesis is not fully understood. BRAF gene encodes B-Raf protein which is an important component of mitogen activated protein kinase (MAPK) pathway. Occurrence of carcinomas is increased by dysregulation of this pathway and gene mutations. BRAF mutations are present in malignant melanoma, colorectal cancer, ovarian carcinoma, papillary thyroid carcinoma and hairy cell leukemia. It is involved in cancer formation. We aimed to determine the presence of BRAF gene mutation in Castleman's Disease and to assess some clinical data of disease and relationship with prognosis. Materials and Methods: In our study tissue samples of 34 patients who were diagnosed as Castleman's Disease between 2007-2014 from 8 different centers are used. Some clinical and laboratory findings of the patients have been evaluated retrospectively. BRAF mutations were evaluated with PCR method. Patient's age, gender, histological type, clinical type, survival, and some laboratory findings were eveluated with statistical analysis. Results: The BRAF gene mutation was not detected in all tissues. The majority of cases (75.6%) were hyaline vascular variant. According to involvement, cases were divided in 3 sites; thoracic, abdominal and cervical. The majority of patients (61.7%) had cervical involvement. 10 of patients had more than one region (29.4%) involvement. The plasma cell variant was significially higher in men (p=0.006). The mean age was significantly higher in the plasma cell group (p=0.006). CRP and sedimentation levels were found significantly higher in plasma cell variant compared to hyaline vascular variant (p<0.05). Hepatomegaly and/or splenomegaly were pesented significially higher in patients with multiple site involvement (p<0.05). Compared to only chemotherapy, 3-year survival was significantly higher in patients treated with only radiotherapy or chemotherapy in addition to radiotherapy (p=0.001). Survival was significantly higher in patients with hyaline vascular variant and one site involvement (p <0.05). Conclusion: This study is the most comprehensive study in our country about Castleman's Disease and we obtained important information about clinical, histopathological and prognostic features of the disease